The CLOCK is the most important element of a digital audio system, working like a heart for human body.

 All the digital audio data inside of digital audio devices are processed and calculated by the clock pulse, communicating the clock signals while also  exchanging audio data with other devices. Particularly, the quality(Jitter) of clock that used in the converting process from digital audio data to analog signals directly affects the corresponding signal making. The audience can feel the purity level of the clock just by listening to the sounds.

 Similarly, the CLOCK shows its presence in every part of digital audio systems, and its quality eventually determines the quality of sound.

 SOtM’s sCLK-xxxx Series Clock, a clock module furnished with all the performance required for high-end digital audio systems, can be used along with modules like the dX-USB HD, iM-USB HD, tX-USBexp, tX-USBhub & others, and may also be used by ordering the corresponding operation clock frequency with devices other than SOtM’s. 

 Those uncertain questions which may be raised as to how much the quality of a clock is important to digital audio devices, why it is recommended to use a high quality clock, how much the sound is improved, and others can be very easily resolved just by listening the sound by installing the sCLK-xxxx into currently used audio devices.

 Even though a clock circuit with reduced jitter within the audible zone is already mounted in most digital audio devices, SOtM’s sCLK-xxxx Series Clock is guaranteed to bring outstanding enhanced audio performance within absolutely crucial mid-high range for audio band operation.

Key Features

  • Ultra low phase noise custom design oscillation circuit
  • Dual clock system for dX-USB HD, iM-USB HD, sMS-1000SQ and etc : Clock select input
  • Single clock system for tX-USBexp, tX-USBhub and etc
  • Wide operating voltage input range
  • Ultra low noise +5V output for system operation : 0.5A max





HD Fever


Operating voltage range
  6.5Vdc ~ 9Vdc (optional 12Vdc input available)
Clock circuit operating Current : 0.3A >
Ultra low noise regulator
Active noise canceller circuit
Transformer isolated clock signal output
Dual independent clock circuit for digital audio system
  sCLK-2224 : 22.5792MHz, 24.576MHz
  sCLK-1124 : 11.2896MHz, 24.576MHz
  Optional other frequency available
Single clock circuit for interface system
  sCLK-12 : 12MHz
  sCLK-48 : 48MHz
  Optional other frequency available
Control input
  Clock select 1 : Low
  Clock select 2 : High
Ultra low noise power output : 5Vdc, 0.5A max


Standard clock 100KHz jitter spectrum

Standard clock 100KHz jitter spectrum

sCLK-2224 100KHz jitter spectrum

sCLK-2224 100KHz jitter spectrum

Standard clock 20KHz jitter spectrum

Standard clock 20KHz jitter spectrum

sCLK-2224 20KHz jitter spectrum

sCLK-2224 20KHz jitter spectrum

The graphs and description was made based on the combo for dX-USB HD& sCLK-2224.

The sCLK-2224 uses ULNR(Ultra Low Noise Regulator) and high performance component like Evox RIFA capacitor, PPS film chip capacitor, discrete device and audio grade OP-AMP. The ULNR is our custom regulation circuit.
When dX-USB HD adds the sCLK-2224, it uses the sCLK-2224’s ULNR for 1’st regulation.

SOtM’s sCLK-2224 has two clock circuit for 44.1KHz domain and 48.0KHz domain.
When one clock circuit operates, the other clock circuit perfectly off(Doesn’t oscillate).
So it doesn’t make random jitter and doesn’t require two ULNR for two clock.

And the sCLK-2224 includes active power noise reduction circuit in clock block. It reduces power noise under 10Hz.

The graphs are jitter spectrum to 100KHz band and zoom into 20KHz.
Spectrum was measured to AES/EBU output connector of dX-USB HD by Stanford Research Systems SR1 audio analyzer..
it is not sCLK-2224 output terminal because some components(clock buffer ic, RS422 driver ic, pulse transformer…) make jitter.

Many clock or audio products specify jitter in ps(Pico Second) and it measured only 12KHz ~ 20MHz band.
It is not include important audio band. So we have to view jitter spectrum.

You should focus under 5KHz band. It is very important band for audio.
Many clock jitter value increase under 10KHz band. Jitter. It is the reason of degrading audio performance.

  • Dual clock system for dX-USB HD, iM-USB HD
  • Single clock system  for tX-USBexp, tX-USBhub
  • Or ask us the customizing clock.

The sCLK sereis clock needs to be connected with power input cable, clock output cable and the clcok select signal cable, but the installation is differ from your own system, you will need ask us the dealer or us about the details.

Yes, please ask us using the email form on our website

Single clock output Qty. 4 1
Dual clock output Qty. (EX. 22.5792MHz <-> 24.576MHz) 4 1
Internal reference clock isolation Yes No
Output clock isolation Yes Yes
Master clock input Yes No
Maser clock input isolation Yes X
Differential clock system Yes No
Frequency configurable by F/W upgrade Yes No

The super clock module, sCLK-EX has been improved a lot from sCLK, even though it is already very good quality clock module, especially the expressions in the ultra low range has been much improved providing much diversity of textures and transparency and also the mid-low range expressions get become significantly plentiful.

And connecting master clock to the sCLK-EX, you are able to make the best possible sound in your audio system.